1. Field of the Invention
This invention relates to keyboard instruments such as electronic pianos that reproduce real key-touch responses (or key-touch feelings or sensations) of acoustic pianos.
2. Description of the Related Art
Conventionally, various types of electronic pianos have been developed and equipped with keyboard mechanisms or structures that can reproduce key-touch responses similar to those produced by keyboards of acoustic pianos.
FIG. 12 is a side view showing an example of a keyboard structure conventionally employed in an electronic piano. That is, a keyboard structure A is basically constituted by a keyboard B containing a prescribed number of keys, a hammer assembly C, an action mechanism D for rotating the hammer assembly C, and a struck portion E struck by the xe2x80x98rotatedxe2x80x99 hammer assembly C. Herein, the action mechanism D substantially corresponds to the known action mechanism of an upright piano.
The hammer assembly C is constituted by a hammer shank C1 and a pseudo hammer C2 that corresponds to a hammer felt of an upright piano. The pseudo hammer C2 is arranged in order to substantially match the weight and balance position (i.e., center of gravity) of the hammer assembly C with those of the hammer assembly of an upright piano. Therefore, the pseudo hammer C2 does not actually strike the struck portion E, but the hammer shank C1 actually strikes the struck portion E.
Actually, an electronic piano comprises sensors and a sound source device (not shown), wherein the sensors detect motions of keys of the keyboard B, and the sound source device is activated to produce electronic sounds based on detection results of the sensors. Thus, the electronic piano can produce prescribed electronic sounds simulating real sounds of an acoustic piano that are produced upon depression of keys causing hammer felts to strike strings.
As described above, the aforementioned electronic piano employs the action mechanism D similar to that of an acoustic piano, and the hammer assembly C that is designed to simulate the weight and balance position of the hammer assembly of an acoustic piano. Therefore, it is possible to produce substantially the same key-touch response of an acoustic piano, wherein the electronic piano can be adjusted in tone volume of sound and produce sound via a headphone set, for example.
The struck portion E is provided mainly for the purpose of reducing striking noise. For this reason, the struck portion E is composed of two sheets of buffer materials such as felts, which are used commonly for all keys of the keyboard B.
This indicates that substantially the same key-touch response is provided with respect to all keys (or registers) of the keyboard B when depressed. In contrast, an acoustic piano produces various key-touch responses with respect to various registers of the keyboard due to arrangement of different types of strings that differ in thickness, material, and tension. Because of the use of buffer materials, the struck portion E may gradually reduce striking force of the hammer assembly C. Therefore, there is a problem in that the key-touch responses produced by the electronic piano upon depression of keys may greatly differ from key-touch responses of an acoustic piano upon depression of keys causing hammer felts to strike strings.
In short, because the aforementioned keyboard instrument such as an electronic piano does not have strings that are struck by hammer felts in an acoustic piano, it may be very difficult to reproduce or accurately simulate real key-touch responses of an acoustic piano, which depend upon deflections (or bends) and weights of strings.
It is an object of the invention to provide a keyboard instrument that can reproduce real key-touch responses, which are produced by an acoustic piano upon depression of keys activating hammer felts to strike strings.
A keyboard instrument such as an electronic piano comprises a keyboard structure that is basically identical to the keyboard structure of an upright piano or the like except hammer assemblies and a struck portion attached to an action bracket. Each of the hammer assemblies is constituted by a hammer shank and a pseudo hammer, one of which is used to strike the struck portion having a multilayer structure including an elastic member (e.g., a plate spring) sandwiched between buffer materials. The elastic member has a prescribed number of striking areas in correspondence with keys arranged on a keybed, wherein the striking areas are gradually increased in weights and bends (or deflections) in a pitch descending order from higher pitches to lower pitches. Concretely, the striking areas are gradually decreased in rigidities (or spring constants) in the pitch descending order. Thus, it is possible to simulate weight factors and bends (or deflections) of strings actually struck by hammer felts in an upright piano, for example.
Upon depression of the keys, the hammer assemblies are rotatably moved towards the struck portion, so that the hammer shanks actually strike the striking areas of the struck portion, wherein the pseudo hammers are used as deadweights actualizing desired weights and balance positions (i.e., center of gravity) of the hammer assemblies in relation to the keys, so that it is possible to simulate key-touch responses of keys of an upright piano. Due to the provision of the buffer materials such as felts, urethanes, leathers, cloths, and synthetic resins, it is possible to optimally reduce striking forces of the hammer assemblies, which in turn contribute to improvements in durability with respect to the hammer assemblies and struck portion.
The elastic member is made of a synthetic resin, or a prescribed metal material that is selected from among stainless steel, nickel silver, phosphor bronze, and brass, for example. In addition, the elastic member has a comb-like opening in which the striking areas are formed between comb teeth respectively and they are gradually increased in dimensions such as lengths in the pitch descending order from higher pitches to lower pitches. Furthermore, the striking areas of the elastic member are curved relative to the hammer assemblies in correspondence with the keys.